Basically, means to just for the person to stop everything he/she is doing and find the nearest gun, point it under their chin and pull the trigger. That way they will no longer bother you and you can get some peace and quiet without their pure bullshit spewing from their mouths. If one continues you to harass you after you say this, you legally have the right to make them discover what your fist tastes like. They cannot sue you for any reason.

A command for someone to get lost (especially from the person that says it), usually as a result of extreme annoyance. Literally it means for them to masturbate themselves, so they aren't inclined to harrass and receive sexual pleasure from the person they are annoying. It's more stinging than "fuck off" because it implies that they could not or should not find anyone else to have sex with, so they need to use the self-manipulation.

When someone tells you to go fuck yourself, they are encouraging you to shove your penis up your own asshole by bending it backwards. Or, if you're a female, to grab the nearest phallic object(s) and penetrate your orifices repeatedly. The connotation is that you'll probably enjoy it and will stop annoying everyone.